Calibration method of line laser profilometer and quantitative evaluation method of optical path deviation.

Abstract

This invention provides a calibration method for a line laser profilometer and a quantitative evaluation method for optical path deviation using the same method. The method includes: adjusting the position and orientation of the actuator to obtain information on the laser line formed by the line laser profilometer at its initial position on the calibration plane and information on the actuator's end effector; translating the actuator to obtain a set of laser line information and a set of actuator end effector information for calibration; and calculating the coordinate transformation relationship between the line laser profilometer and the actuator end effector based on the above information. The technical solution of this invention directly calibrates the position and geometric features of the laser plane, thereby facilitating accurate control of the laser position and orientation of the line laser profilometer. This avoids using quantitative data from the profilometer for feature calculations, improving calibration accuracy. Furthermore, it eliminates the need for high-precision three-dimensional calibration blocks, reducing the requirements for calibration materials and the complexity of the calibration process.

Description

Technical Field

[0001] This invention relates to the field of laser calibration technology, and in particular to a calibration method for a line laser profilometer and a method for quantitatively evaluating optical path deviation using the same. Background Technology

[0002] Laser profilometers measure 3D data by mapping the contours of an object onto a laser plane. In high-precision robot operations and data stitching measurements, precise control of the laser plane's pose is essential. For example, in industrial robot systems, line laser profilometers are often used for precise scanning of local areas during high-precision welding or cutting, or to simulate the tool's posture to inspect the target's working path and obtain accurate feature information within a local area. During these operations, it is desirable that the actual operating pose of the laser line or the plane containing the laser precisely coincides with the planned direction. To control sampling accuracy or time consumption, the distance between the line laser profilometer and the object must be controlled to adjust the acquisition width of each laser profile. For instance, when using two profilometers to measure the thickness of an object, ideally, the line laser profilometer should be perpendicular to the object's surface, and the laser planes of the two profilometers should coincide. When installing a line laser profilometer at the end effector for collaborative operation, hand-eye calibration is required to obtain the transformation relationship between different coordinate systems. Because the laser profilometer's imaging structure captures point cloud data, its calibration method for the coordinate transformation relationship with the actuator differs from traditional camera hand-eye calibration.

[0003] Several line laser calibration methods exist in the prior art. For example, patent document CN116734730A proposes a machine tool line laser calibration method based on a standard sphere. A profilometer scans the entire standard sphere from different directions to collect scanning data. Based on the 3D point cloud data from each scan, the sphere center coordinates corresponding to each point cloud in different scanning directions are extracted. Based on the scanning direction and the sphere center coordinates, the rotation and translation RT matrix is ​​calculated to obtain the relative positional relationship of the line laser relative to the machine tool spindle, thus completing the line laser calibration. Patent document CN114670203A proposes a laser vision-guided robot automatic welding hand-eye calibration method. This method designs a customized 3D calibration board with three calibration points. The moving robot arm collects the line laser calibration lines projected onto the 3D calibration board through a line laser sensor, obtaining calibration feature points and completing the hand-eye calibration. Patent document CN... Patent 117073582A proposes a calibration method, device, and electronic equipment for a line laser profilometer system. It uses a moving axis to drive a calibration ball / laser profilometer, and calibrates the system consisting of the line laser profilometer and the moving axis by fitting the center of multiple obtained cross-sectional circles. Patent document CN115284330A describes a method for calibrating a laser profilometer for a welding robot. This method uses measurement to calibrate the origin of the laser profilometer's coordinate system, simultaneously leveling the profilometer and calibration surface using a level and profilometer line, and applying the ABC-2 point method to calibrate the laser profilometer's coordinate system attitude. Current line laser calibration methods do not directly calibrate the geometric features of the laser plane. Instead, they assume that the line laser profilometer, the CMOS or CCD imaging plane's X-axis, and the lens and laser are in ideal installation states. They rely on the coordinate data of the line laser profilometer line to calculate feature values ​​or assess the profilometer's position / state (e.g., horizontal with the calibration surface). When the internal optical structure of the profilometer, such as a non-parallel lens, changes occur during transportation or long-term use, or the profilometer's own measurement results have errors, the calibration results will be affected. In addition, most existing methods require the customization of standard-shaped 3D calibration blocks, such as calibration spheres, cones, trapezoidal frustums, or customized 3D calibration plates with structural and feature point characteristics. These methods place high demands on the calibration objects. For example, standard sphere calibration objects require spheres with high machining accuracy. Customized 3D calibration plates have complex structures and high processing costs. Summary of the Invention

[0004] This invention aims to solve the above problems by providing a calibration method for a line laser profilometer and an optical error inspection method using the same. The method directly calibrates the position and geometric feature information of the laser plane, so as to accurately control the laser position and attitude of the line laser profilometer. It avoids the use of quantitative data from the profilometer to calculate features, improves calibration accuracy, eliminates the need for high-precision three-dimensional calibration blocks, and reduces the requirements for calibration objects and the complexity of calibration.

[0005] The present invention solves the aforementioned problem by employing the following technical solution: a line laser profilometer calibration method, comprising an actuator, a line laser profilometer, and a calibration plane. The line laser profilometer is mounted on the end of the actuator and is used to project a line laser beam onto the calibration plane, forming a laser line on the calibration plane. The coordinate system of the line laser profilometer is set according to the geometric characteristics of the laser plane of the line laser profilometer, wherein the directions of the two axes are parallel to the normal direction of the plane containing the laser beam and the direction of the laser angle bisector of the line laser profilometer, respectively, and the origin is the intersection point of the laser beams. The line laser profilometer calibration method includes the following steps:

[0006] Sa adjusts the pose of the actuator to obtain the laser line information formed by the line laser profilometer on the calibration plane at the initial position and the actuator end information:

[0007] Sa1 controls the actuator to adjust its posture, driving the line laser profilometer to move so that the laser line endpoint falls within the preset area of ​​the calibration plane, forming a laser line R0 (i=0); at this time, the position of the laser origin of the line laser profilometer is the initial position Q0.

[0008] Sa2 records the laser line information L0 (i=0) and the actuator end information W0 at the initial position Q0;

[0009] The laser line information L0 includes the coordinates of M0 points on the line R0 in the first coordinate system, where M0 ≥ 2, and the M0 points on the line R0 include the two endpoints of the line R0.

[0010] The actuator end effector information W0 includes the actuator end effector center coordinates P in the first coordinate system. 0， And the transformation matrix H0 between the current actuator end coordinate system T0 and the first coordinate system;

[0011] Sb translates the actuator to obtain a set of linear laser information for calibration and a set of actuator end effector information:

[0012] The actuator is controlled to move the line laser profilometer to N positions, where N ≥ 1, and at each position Q i (1≤i≤N) Ensure that the endpoint of the laser line falls within the preset area of ​​the calibration plane;

[0013] Q at each position i Record the laser line R at this location. i The laser line information L corresponding to (1≤i≤N) i and end-of-line information of the executing agency W i ;

[0014] The laser line information Li Including M i A straight line R i The coordinates of the point on the first coordinate system, M i ≥2, the M i A straight line R i The points on the line include the line R. i The two endpoints;

[0015] The actuator end information W i Including the coordinates P of the actuator end effector center in the first coordinate system i (1≤i≤N);

[0016] The set of center coordinates of the actuator end point {P i If i ≥ 0, then i is not on a plane parallel to the calibration plane.

[0017] Sc line laser profilometer - coordinate transformation relationship of actuator end effector:

[0018] Sc1 obtains the normal to the plane containing the laser from the line laser profilometer: through the set of center coordinates of the actuator end effector {P}. i The set of laser linear coordinate information {L, i≥0} and i≥0} i Fit the plane equation of the laser origin of the line laser profilometer at position Q0, and obtain the normal of the plane where the laser of the line laser profilometer is located through the plane equation.

[0019] Sc2 obtains the origin of the line laser profilometer: through the set of center coordinates of the actuator end effector {P} i The set of laser linear coordinate information {L, i≥0} and i≥0} i The coordinate information of the endpoints of the straight lines in {i≥0} is used to obtain the left and right boundary profile lines of the laser projection plane of the line laser profilometer at the position Q0. The intersection of the lines is the origin of the line laser profilometer.

[0020] Sc3 obtains the laser angle bisector of the line laser profiler: the laser angle bisector is calculated through the left and right boundary profile lines;

[0021] Sc4 obtains the pose of the line laser profiler in the first coordinate system at position Q0 by using the normal of the plane where the laser of the line laser profiler is located, the laser angle bisector of the line laser profiler, and the origin of the line laser profiler.

[0022] Sc5 obtains the coordinate transformation relationship between the line laser profilometer and the end of the actuator through the transformation matrix H0 between the coordinate system at the end of the actuator and the first coordinate system.

[0023] Through the set of center coordinates of the actuator end point {P i The set of laser linear coordinate information {L, i≥0} and i≥0}i The plane equations for the laser at position Q0, i≥0, fitted by the laser profilometer include:

[0024] Based on the set of center coordinates of the actuator end effector {P i Get the position Q (i≥0). i The translation value T of the relative position Q0 i ;

[0025] via -T i Acquire equivalent straight line information L from the non-translation calibration plane of the line laser profilometer under relative translational state. i ';

[0026] Through the information set of equivalent straight lines {L i By fitting the coordinates of the points in ',i≥0}, the equation of the plane where the line laser profilometer laser is located at position Q0 is obtained; the plane normal is obtained through the plane equation.

[0027] Through the set of center coordinates of the actuator end point {P i The set of laser linear coordinate information {L, i≥0} and i≥0} i The coordinate information of the endpoints of the straight lines in the range i≥0 is used to obtain the left and right boundary contour lines of the laser projection plane of the line laser profilometer, including:

[0028] Based on the set of center coordinates of the actuator end effector {P i Get the position Q (i≥0). i The translation value T of the relative position Q0 i ;

[0029] By using the equation of the plane where the line laser profilometer is located at position Q0 and T i Calculate the position Q i The intersection line LC of the laser plane and the calibration plane of the time-line laser profilometer i (i≥0);

[0030] Calculate the laser line R i The line of intersection LC of the two endpoints of (i≥0) on the calibration plane i Projected coordinates LPl on i and LPR i ;

[0031] via -T i Translation projection coordinates LPl i and LPR i Obtain the coordinates of the left endpoint LPl of the equivalent straight line at position Q0 under the state of relative translation between the non-translated calibration plane and the laser profilometer. i 'and the coordinates of the right endpoint of the equivalent line LPR i ';

[0032] For all laser lines R i Calculate LPl i 'and LPR i ', obtain the set of coordinates of the left endpoints of the equivalent lines {LPl i The set of coordinates of the right endpoints of the equivalent lines {LPR} and ',i≥0} i ',i≥0};

[0033] Through the set {LPl i ',i≥0} and set {LPR i ',i≥0}, obtain the left and right boundary profile lines of the laser projection plane of the line laser profilometer at the position Q0.

[0034] The laser line information L i (i≥0), the laser line R is marked manually. i The feature points are obtained by teaching and marking the feature points on the actuator; or by setting a calibration camera above the calibration plane to acquire data containing the complete laser line R. i After the image is processed, the laser line coordinate information is obtained through the recognition module. The laser line R is then calculated using the transformation relationship between the first coordinate system and the calibration camera coordinate system. i The coordinates of a point on the first coordinate system.

[0035] It also includes: obtaining the laser subtendant angle of the line laser profiler through the straight lines of the left and right boundary contours.

[0036] Also includes: Sd obtains the minimum imaging height of the line laser profilometer:

[0037] By using the coordinate transformation relationship between the line laser profilometer and the actuator end, the line laser profilometer is adjusted to be parallel to the coordinate system axis of the calibration plane, wherein the normal of the plane in which the laser of the line laser profilometer is located is parallel to the calibration plane;

[0038] Adjust the line laser profilometer to be close to the calibration plane, observe the profilometer line, and record the value of the laser origin of the line laser profilometer in the calibration plane coordinate system when the profilometer line disappears. This value is the minimum imaging height.

[0039] The calibration plane is provided with a calibration evaluation line; the Sc step, which obtains the coordinate transformation relationship between the line laser profilometer and the actuator end, also includes:

[0040] Based on the coordinate transformation relationship between the line laser profilometer and the end effector obtained in step Sc5, calculate the pose H of the line laser profilometer when it projects the laser onto the mark evaluation line. L ;

[0041] Based on H L Adjust the position of the actuator;

[0042] Observe the overlap between the laser line projected onto the calibration plane by the line laser profilometer and the calibration evaluation line; if the overlap is greater than the threshold, repeat steps Sa to Sc; if the overlap is less than the threshold, the calibration is complete.

[0043] The first coordinate system is the actuator base coordinate system or the calibration plane coordinate system.

[0044] A quantitative evaluation method for optical path deviation of a line laser profilometer is provided, which uses the aforementioned line laser profilometer calibration method to obtain the coordinate transformation relationship between the line laser profilometer and the end of the actuator.

[0045] By transforming the coordinates of the line laser profiler and the actuator end, the attitude of the line laser profiler relative to the calibration plane is adjusted so that the normal of the plane in which the laser of the line laser profiler is located is parallel to the calibration plane, and the direction of the laser angle bisector of the line laser profiler is parallel to the calibration plane.

[0046] Adjust the distance between the line laser profilometer and the calibration plane so that the profile line appears in the acquisition software interface of the line laser profilometer;

[0047] Calculate the angle between the contour line and the horizontal coordinate axis of the acquisition software interface to obtain the x-axis installation angle error of the imaging plane of the line laser profilometer;

[0048] Obtain the coordinates of the midpoint of the contour line in the imaging coordinate system of the online laser profilometer. Combine this with the height value of the line laser profilometer relative to the calibration plane, and calculate the coordinate difference between the origin of the profilometer imaging coordinate system and the origin of the line laser profilometer calibration coordinate system in the corresponding axis direction.

[0049] The beneficial effects of this invention are: it directly calibrates the position and geometric features of the laser plane, constructs a coordinate system by using the normal vector of the laser plane, the laser angle bisector, and the origin of the laser profilometer, and directly calibrates the physical spatial position of the plane where the line laser is located. This is more in line with the intuitive understanding of the line laser imaging plane in the principle of the line laser profilometer, and facilitates accurate control of the attitude of the line laser profilometer, so that the calibrated laser line profile can be projected onto the target path according to the predetermined design.

[0050] There is no need to use high-precision 3D calibration blocks. Laser plane calibration information can be obtained through conventional calibration methods of the actuator and the position and pose information of the actuator end effector. This avoids the need to use quantitative data calculation of profilometers to calculate features, improves calibration accuracy, and helps with subsequent operations such as measurement, safety inspection, and adaptive scanning planning.

[0051] The geometric shape information of the emitted laser is calibrated to obtain the physical origin and divergence angle of the plane where the line laser is located. The positional relationship between the profilometer and the object can be adaptively adjusted according to the sampling accuracy or time consumption requirements, thereby adjusting the acquisition width of the laser profile on the target object.

[0052] By designing calibration steps and using iterative error assessment methods, the errors in mechanical calibration are reduced.

[0053] By checking the installation error of the profilometer's imaging plane through the calibrated coordinate transformation relationship between the line laser profilometer and the actuator end, the reliability of the profilometer data can be evaluated and whether the installation position needs to be adjusted.

[0054] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0055] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0056] Figure 1 This is a schematic diagram of the implementation environment of the present invention;

[0057] Figure 2 This is a flowchart of the laser profilometer calibration method in this invention;

[0058] Figure 3 A schematic diagram showing the translation of the laser profilometer and the endpoint of the laser line falling within a preset area of ​​the calibration plane;

[0059] Figure 4 This is a schematic diagram illustrating the acquisition of equivalent straight line information of a line laser profilometer under a relative translational state of the calibration plane without translation, in one embodiment of the invention. Detailed Implementation

[0060] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example 1

[0061] Figure 1 The diagram illustrates the implementation environment of the line laser profilometer calibration method of the present invention, which includes an actuator 1, a line laser profilometer 2, and a calibration plane 3. The line laser profilometer 2 is mounted on the actuator 1 and is used to project a line laser onto the calibration plane 3, thereby forming a laser line on the calibration plane 3.

[0062] In one common embodiment, the line laser profilometer is mounted at the end of the actuator; it can also be mounted on other axes of the actuator, provided that the coordinate values ​​of that axis can be calculated.

[0063] The actuator can be a robotic arm, robotic hand, or other mechanism.

[0064] The coordinate system of the line laser profilometer is set according to the geometric characteristics of the laser plane of the line laser profilometer. The directions of the two axes are parallel to the normal of the plane where the laser of the line laser profilometer is located and the direction of the laser angle bisector of the line laser profilometer, respectively. The origin is the position of the intersection of the laser rays.

[0065] A method for calibrating a line laser profilometer, such as Figure 2 As shown, it includes the following steps:

[0066] Sa adjusts the actuator's pose and acquires the laser line information formed by the initial position line laser profilometer on the calibration plane and the actuator's end effector information:

[0067] Sa1 controls the actuator to adjust its posture, driving the line laser profilometer to move so that the laser line endpoint falls within the preset area of ​​the calibration plane, forming a laser line R0 (i=0); at this time, the position of the laser origin of the line laser profilometer is the initial position Q0.

[0068] Sa2 records the laser line information L0 (i=0) and the actuator end information W0 at the initial position Q0;

[0069] The laser line information L0 includes the coordinates of M0 points on the line R0 in the first coordinate system, where M0 ≥ 2, and the M0 points on the line R0 include the two endpoints of the line R0.

[0070] The actuator end information W0 includes the actuator end center coordinates P0 in the first coordinate system, and the transformation matrix H0 between the current actuator end coordinate system T0 and the first coordinate system;

[0071] Sb translates the actuator to obtain the set of linear laser information for calibration and the set of actuator end effector information:

[0072] The control actuator drives the linear laser profilometer to translate N positions, where N≥1, and at each position Q i (1≤i≤N) Ensure that the endpoint of the laser line falls within the preset area of ​​the calibration plane;

[0073] Q at each position i Record the laser line R at this location. i The laser line information L corresponding to (1≤i≤N) i and end-of-line information of the executing agency W i ;

[0074] The laser line information L i Including M i A straight line R i The coordinates of the point on the first coordinate system, M i ≥2, the M i A straight line R i The points on the line include the line R. i The two endpoints;

[0075] The actuator end information W i Including the coordinates P of the actuator end-effector center in the first coordinate system i (1≤i≤N);

[0076] The set of center coordinates of the actuator end point {P i If i ≥ 0, then i is not on a plane parallel to the calibration plane.

[0077] Sc line laser profilometer - coordinate transformation relationship of actuator end effector:

[0078] Sc1 obtains the normal to the plane containing the laser from the line laser profilometer: through the set of center coordinates of the actuator end effector {P}. i The set of laser linear coordinate information {L, i≥0} and i≥0} i Fit the plane equation of the laser origin of the line laser profilometer at position Q0, and obtain the normal of the plane where the laser of the line laser profilometer is located through the plane equation.

[0079] Sc2 obtains the origin of the line laser profilometer: through the set of center coordinates of the actuator end effector {P} i The set of laser linear coordinate information {L, i≥0} and i≥0} i The coordinate information of the endpoints of the straight lines in {i≥0} is used to obtain the left and right boundary profile lines of the laser projection plane of the line laser profilometer at the position Q0. The intersection of the lines is the origin of the line laser profilometer.

[0080] Sc3 obtains the laser angle bisector of the line laser profiler: the laser angle bisector is calculated through the left and right boundary profile lines;

[0081] Sc4 obtains the pose of the line laser profiler in the first coordinate system at position Q0 by using the normal of the plane where the laser of the line laser profiler is located, the laser angle bisector of the line laser profiler, and the origin of the line laser profiler.

[0082] Sc5 obtains the coordinate transformation relationship between the line laser profilometer and the end of the actuator through the transformation matrix H0 between the coordinate system at the end of the actuator and the first coordinate system.

[0083] The third axis is obtained by cross product of the normal vector n and the laser angle bisector. The resulting coordinate system of the laser profilometer better matches the intuitive understanding of the line laser imaging plane in the principle of line laser profilometers, facilitating accurate control of the attitude of the line laser profilometer and its distance from the target surface. Furthermore, due to direct calibration with the actuator, the accuracy is higher.

[0084] In one embodiment, information about the plane can be calibrated by the actuator, such as by the three-point method.

[0085] The aforementioned first coordinate system remains unchanged during the movement of the actuator end coordinate system. The first coordinate system can be the actuator base coordinate system or the calibration plane coordinate system, but since the position of the actuator end coordinate system in the scene is dynamically changing, the actuator end coordinate system cannot be selected as the first coordinate system.

[0086] In a specific implementation, the set of center coordinates of the actuator end point {P} i The set of laser linear coordinate information {L, i≥0} and i≥0} i The plane equations for the laser at position Q0, i≥0, fitted by the laser profilometer include:

[0087] Based on the set of center coordinates of the actuator end effector {P i Get the position Q (i≥0). i The translation value T of the relative position Q0 i As mentioned above, position Q i With relative position Q0, the line laser profilometer undergoes translation, relative to coordinate P. i The translation value T can be obtained by calculating the difference between the coordinate P0 and P0. i Translation details and translation value T i like Figure 3 As shown; Figure 3 The laser profilometer is illustrated by a cylinder, while the laser plane is illustrated by a triangle. The two sides of the triangle are the left and right contour lines of the laser, and the base of the triangle is the laser line formed by the intersection of the laser plane and the calibration plane.

[0088] like Figure 4 As shown, via -T i Acquire equivalent straight line information L from the non-translation calibration plane of the line laser profilometer under relative translational state. i ';Through the equivalent linear information set {L i For all coordinate points in the range ', i≥0}, fit the equation of the plane where the line laser profilometer laser is located at position Q0; obtain the plane normal through the plane equation.

[0089] Because lasers have a limited width, and manual alignment also introduces some error, if only multiple P... iPoint fitting is problematic if the number of points is too small, resulting in significant errors. This method uses points along a straight line for fitting, ensuring a larger number of points and that the fitted plane lies on the average plane of all laser line points.

[0090] In a specific implementation, the set of center coordinates of the actuator end point {P} i The set of laser linear coordinate information {L, i≥0} and i≥0} i The coordinate information of the endpoints of the straight lines in the range i≥0 is used to obtain the left and right boundary contour lines of the laser projection plane of the line laser profilometer, including:

[0091] Based on the set of center coordinates of the actuator end effector {P i Get the position Q (i≥0). i The translation value T of the relative position Q0 i ;

[0092] By using the equation of the plane where the line laser profilometer is located at position Q0 and T i Calculate the position Q i The intersection line LC of the laser plane and the calibration plane of the time-line laser profilometer i (i≥0); Here, LCI is the intersection line in a scenario where the line laser profilometer moves and the calibration plane remains stationary;

[0093] Calculate the laser line R i The line of intersection LC of the two endpoints of (i≥0) on the calibration plane i Projected coordinates LPl on i and LPR i ;

[0094] via -T i Translation projection coordinates LPl i and LPR i Obtain the coordinates of the left endpoint LPl of the equivalent straight line at position Q0 under the state of relative translation between the non-translated calibration plane and the laser profilometer. i 'and the coordinates of the right endpoint of the equivalent line LPR i ';

[0095] For all laser lines R i Calculate LPl i 'and LPR i ', obtain the set of coordinates of the left endpoints of the equivalent lines {LPl i The set of coordinates of the right endpoints of the equivalent lines {LPR} and ',i≥0} i ',i≥0};

[0096] Through the set {LPl i ',i≥0} and set {LPR i',i≥0}, obtain the left and right boundary profile lines of the laser projection plane of the line laser profilometer at the position Q0.

[0097] Because lasers have width, the endpoints of a straight line directly connected to the laser may not necessarily be in the same plane, and the lines at the left and right endpoints may not necessarily intersect. However, in this implementation method, the endpoints projected onto the intersection line are all in the same plane. After fitting the straight line, it can be ensured that they intersect in the plane to obtain the laser origin of the line laser profiler.

[0098] On the other hand, if the laser rays are directly projected onto the plane where the laser profilometer is located, they may not necessarily fall on the equivalent calibration plane. Since physical straight lines are all on the calibration plane, this implementation method chooses to project onto the intersection line of the calibration plane and the plane where the laser profilometer is located.

[0099] In a specific implementation, the laser linear information L i (i≥0), the laser line R is marked manually. i The feature points are obtained by teaching and marking the feature points using the actuator; information about the laser line is obtained using the actuator, such as by acquiring the set of coordinate information of feature points on the marked line / laser line in the robot's base coordinate system or calibration plane coordinate system through a calibration probe. The feature points can be endpoints of the line or marks of points on the laser line recorded on the calibration plane. By using the actuator alone, a certain degree of calibration accuracy can still be achieved in scenarios where calibration tools are lacking, reducing dependence.

[0100] In another specific implementation, a calibration camera is set up above the calibration plane to capture images containing the complete laser line R. i After the image is processed, the laser line coordinate information is obtained through the recognition module. The laser line R is then calculated using the transformation relationship between the first coordinate system and the calibration camera coordinate system. i The coordinates of the point on the first coordinate system. Using a calibration camera, since the calibration camera has been accurately calibrated in advance, the accuracy is more stable and controllable.

[0101] The first coordinate system can be the actuator base coordinate system or the calibration plane coordinate system. Here, the actuator base coordinate system is used as an example: the relationship between the calibration camera and the actuator is accurately calibrated in advance. After the actuator moves the line laser profilometer into place, the camera acquires an image containing the laser line. The set of laser points on the plane is obtained through the recognition module. The set of laser line coordinate information is obtained through the relationship between the calibration plane, the set of laser points, and the camera-actuator.

[0102] In one embodiment, the distance between the profilometer and the object surface can be quantitatively controlled by the laser divergence angle, the expected line laser acquisition width, and the coordinate transformation relationship between the line laser profilometer and the actuator end. The laser divergence angle can be calculated from the left and right boundary profile lines.

[0103] In another embodiment, after obtaining the coordinate transformation relationship between the line laser profilometer and the actuator end, the following steps are also included: Sd obtains the minimum imaging height of the line laser profilometer; through the coordinate transformation relationship between the line laser profilometer and the actuator end, the line laser profilometer is adjusted to be parallel to the axis of the calibration plane coordinate system, wherein the normal of the plane where the laser of the line laser profilometer is located is parallel to the calibration plane; the line laser profilometer is adjusted to be close to the calibration plane, the profilometer is observed, and the value of the laser origin of the line laser profilometer in the calibration plane coordinate system when the profilometer disappears is recorded, which is the minimum imaging height.

[0104] Obtaining the minimum imaging height of a line laser profilometer allows for quantitative control of the distance between the profilometer and the object surface.

[0105] After initially obtaining the coordinate transformation relationship between the line laser profilometer and the actuator end, the calibration information can be evaluated. If the evaluation result meets the preset requirements, the calibration is complete; otherwise, it needs to be re-evaluated.

[0106] In one specific embodiment, the calibration results are evaluated in the following manner:

[0107] A calibration evaluation line is set on the calibration plane. The calibration evaluation line can be a drawn line or an etched line, depending on the requirements. The pose information of the calibration evaluation line is pre-calibrated.

[0108] Based on the coordinate transformation relationship between the line laser profilometer and the end effector obtained from Sc5, the pose H of the line laser profilometer when projecting the laser onto the mark evaluation line is calculated. L ;

[0109] Based on H L Adjust the position of the actuator;

[0110] Observe the overlap between the laser line projected by the line laser profilometer onto the calibration plane and the calibration evaluation line; if the overlap is greater than the threshold, repeat steps Sa-Sc; if the overlap is less than the threshold, the calibration is considered complete. Example 2

[0111] This embodiment provides a method for quantitatively evaluating the optical path deviation of a line laser profilometer, comprising the following steps:

[0112] S1 Adjust the actuator pose and acquire the laser line information formed by the initial position line laser profilometer on the calibration plane and the actuator end effector information:

[0113] S2 translates the actuator to obtain the set of linear laser information for calibration and the set of actuator end effector information:

[0114] S3 Line Laser Profilometer - Coordinate Transformation Relationship of Actuator End:

[0115] S4 adjusts the attitude of the line laser profiler relative to the calibration plane by transforming the coordinates of the line laser profiler and the end of the actuator, so that the normal of the plane in which the laser of the line laser profiler is located is parallel to the calibration plane, and the direction of the laser angle bisector of the line laser profiler is parallel to the calibration plane.

[0116] Adjust the distance between the line laser profilometer and the calibration plane so that the profile line appears in the acquisition software interface of the line laser profilometer;

[0117] Calculate the angle between the contour line and the horizontal coordinate axis of the acquisition software interface to obtain the x-axis installation angle error of the imaging plane of the line laser profilometer;

[0118] The imaging plane of a line laser profilometer is generally the imaging direction of a CMOS or CCD chip.

[0119] Obtain the coordinates of the midpoint of the contour line in the imaging coordinate system of the online laser profilometer. Combine this with the height value of the line laser profilometer relative to the calibration plane, and calculate the coordinate difference between the origin of the profilometer imaging coordinate system and the origin of the line laser profilometer calibration coordinate system in the corresponding axis direction.

[0120] The midpoint of the contour line is the vertical projection point of the line laser profilometer on the calibration plane. Its coordinates in the line laser profilometer are (0, h), and its coordinates in the imaging coordinate system of the line laser profilometer are (x, z). The calculated difference is the difference between the origin of the imaging coordinate system of the line laser profilometer (2D plane, generally XZ value, corresponding to the laser plane) and the origin of the coordinate system calibrated according to the geometric characteristics of the laser plane in the plane where the laser is located.

[0121] Compared with existing technologies, this technical solution directly calibrates the geometric feature information of the laser plane. A coordinate system is constructed using the normal vector of the laser plane, the laser angle bisector, and the origin of the laser profilometer. This directly calibrates the physical spatial position of the plane containing the line laser, better matching the intuitive understanding of the line laser imaging plane in the principle of line laser profilometers. This facilitates accurate control of the line laser profilometer's attitude, ensuring that the calibrated laser line profile is projected onto the target path according to the predetermined design. It eliminates the need for high-precision 3D calibration blocks, obtaining laser plane calibration information through conventional calibration methods of the actuator and the end effector's pose information. This avoids the need for quantitative data calculations in the profilometer, improving calibration accuracy and aiding subsequent operations such as measurement, safety checks, and adaptive scan planning. By calibrating the geometric shape information of the emitted laser and obtaining the physical origin and divergence angle of the plane containing the line laser, the positional relationship between the profilometer and the object can be adaptively adjusted according to sampling accuracy or time requirements, thereby adjusting the acquisition width of the laser profile on the target object. The designed calibration steps and error evaluation iterative methods reduce mechanical calibration errors. By checking the installation error of the profilometer's imaging plane through the calibrated coordinate transformation relationship between the line laser profilometer and the actuator end, the reliability of the profilometer data can be evaluated and whether the installation position needs to be adjusted.

[0122] Furthermore, it should be understood that the above embodiments only illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for calibrating a line laser profilometer, comprising an actuator, a line laser profilometer, and a calibration plane, wherein the line laser profilometer is mounted on the end of the actuator, and the line laser profilometer is used to project a line laser onto the calibration plane and form a laser line on the calibration plane; characterized in that, The coordinate system of the line laser profilometer is set according to the geometric characteristics of the laser plane of the line laser profilometer. The directions of the two axes are parallel to the normal to the plane containing the laser beam and the direction of the laser angle bisector, respectively. The origin of the coordinate system is the intersection of the two boundary profile lines, i.e., the location of the laser ray intersection point. The line laser profilometer calibration method includes the following steps: Sa adjusts the pose of the actuator to obtain the laser line information formed by the line laser profilometer on the calibration plane at the initial position and the actuator end information: Sa1 controls the actuator to adjust its posture, driving the line laser profilometer to move so that the laser line endpoint falls within the preset area of ​​the calibration plane, forming a laser line R0; at this time, the position of the laser origin of the line laser profilometer is the initial position Q0. Sa2 records the laser line information L0 and the actuator end information W0 at the initial position Q0; The laser line information L0 includes the coordinates of M0 points on the line R0 in the first coordinate system, M0≥2, and the M0 points on the line R0 include the two endpoints of the line R0. The first coordinate system is the actuator base coordinate system or the calibration plane coordinate system. The actuator end effector information W0 includes the actuator end effector center coordinates P in the first coordinate system. 0， And the transformation matrix H0 between the current actuator end coordinate system T0 and the first coordinate system; Sb translates the actuator to obtain a set of linear laser information for calibration and a set of actuator end effector information: The actuator is controlled to move the line laser profilometer to N positions, where N≥1. The positions after translation are denoted as Q1, Q2, …, Q. N ; at each position Q i Where i = 1, 2, …, N, all ensuring that the endpoints of the laser lines fall within the preset area of ​​the calibration plane; Q at each position i Record the laser line R at this location. i and its corresponding laser line information L i and end-of-line information of the executing agency W i , where i = 1, 2, …, N; The laser line information L i Including M i A straight line R i The coordinates of the point on the first coordinate system, M i ≥2, the M i A straight line R i The points on the line include the line R. i The two endpoints; The actuator end information W i Including the coordinates P of the actuator end effector center in the first coordinate system i , where i = 1, 2, …, N; The set of center coordinates of the actuator end point {P i If i ≥ 0, then i is not on a plane parallel to the calibration plane. Sc line laser profilometer - coordinate transformation relationship of actuator end effector: Sc1 obtains the normal to the plane containing the laser from the line laser profilometer: through the set of center coordinates of the actuator end effector {P}. i The set of laser linear coordinate information {L, i≥0} and i≥0} i Fit the plane equation of the laser origin of the line laser profilometer at position Q0, and obtain the normal of the plane where the laser of the line laser profilometer is located through the plane equation. Sc2 obtains the origin of the line laser profilometer: through the set of center coordinates of the actuator end effector {P} i The set of laser linear coordinate information {L, i≥0} and i≥0} i The coordinate information of the endpoints of the straight lines in {i≥0} is used to obtain the left and right boundary profile lines of the laser projection plane of the line laser profilometer at the position Q0. The intersection of the lines is the origin of the line laser profilometer. Sc3 obtains the laser angle bisector of the line laser profiler: the laser angle bisector is calculated through the left and right boundary profile lines; Sc4 obtains the pose of the line laser profiler in the first coordinate system at position Q0 by using the normal of the plane where the laser of the line laser profiler is located, the laser angle bisector of the line laser profiler, and the origin of the line laser profiler. Sc5 obtains the coordinate transformation relationship between the line laser profilometer and the end of the actuator through the transformation matrix H0 between the coordinate system at the end of the actuator and the first coordinate system.

2. The calibration method for a line laser profilometer as described in claim 1, characterized in that, Through the set of center coordinates of the actuator end point {P i The set of laser linear coordinate information {L, i≥0} and i≥0} i The plane equations for the laser at position Q0, i≥0, fitted by the laser profilometer include: Based on the set of center coordinates of the actuator end effector {P i Get the position Q (i≥0). i The translation value T of the relative position Q0 i ; via -T i Acquire equivalent straight line information L from the non-translation calibration plane of the line laser profilometer under relative translational state. i '; Through the information set of equivalent straight lines {L i By fitting the coordinates of the points in ',i≥0}, the equation of the plane where the line laser profilometer laser is located at position Q0 is obtained; the plane normal is obtained through the plane equation.

3. The calibration method for a line laser profilometer as described in claim 2, characterized in that, Through the set of center coordinates of the actuator end point {P i The set of laser linear coordinate information {L, i≥0} and i≥0} i The coordinate information of the endpoints of the straight lines in the range i≥0 is used to obtain the left and right boundary contour lines of the laser projection plane of the line laser profilometer, including: Based on the set of center coordinates of the actuator end effector {P i Get the position Q (i≥0). i The translation value T of the relative position Q0 i ; By using the equation of the plane where the line laser profilometer is located at position Q0 and T i Calculate the position Q i The intersection line LC of the laser plane and the calibration plane of the time-line laser profilometer i , where i = 0, 1, …, N; Calculate the laser line R i , where i = 0, 1, …, N, and the intersection line LC of the two endpoints on the calibration plane. i Projected coordinates LPl on i and LPR i , where i = 0, 1, …, N; via -T i Translation projection coordinates LPl i and LPR i Obtain the coordinates of the left endpoint LPl of the equivalent straight line at position Q0 under the state of relative translation between the non-translation calibration plane and the laser profilometer. i 'and the coordinates of the right endpoint of the equivalent line LPR i '; For all laser lines R i Calculate LPl i 'and LPR i ', obtain the set of coordinates of the left endpoints of the equivalent lines {LPl i The set of coordinates of the right endpoints of the equivalent lines {LPR} and ',i≥0} i ',i≥0}; Through set {LPl i ',i≥0} and set {LPR i ',i≥0}, obtain the left and right boundary profile lines of the laser projection plane of the line laser profilometer at the position Q0.

4. The calibration method for a line laser profilometer as described in claim 1, characterized in that, The laser line information L i Where i = 0, 1, …, N, and the laser line R is manually marked. i The feature points are obtained by teaching and marking the feature points on the actuator; or by setting a calibration camera above the calibration plane to acquire data containing the complete laser line R. i After the image is processed, the laser line coordinate information is obtained through the recognition module. The laser line R is then calculated using the transformation relationship between the first coordinate system and the calibration camera coordinate system. i The coordinates of a point on the first coordinate system.

5. The calibration method for a line laser profilometer as described in claim 1, characterized in that, Also includes: The laser angle of the line laser profiler is obtained by passing through the straight lines of the left and right boundary contours.

6. The calibration method for a line laser profilometer as described in claim 1, characterized in that, Also includes: Sd obtains the minimum imaging height for the line laser profilometer: By using the coordinate transformation relationship between the line laser profilometer and the actuator end, the line laser profilometer is adjusted to be parallel to the coordinate system axis of the calibration plane, wherein the normal of the plane in which the laser of the line laser profilometer is located is parallel to the calibration plane; Adjust the line laser profilometer to be close to the calibration plane, observe the profilometer line, and record the value of the laser origin of the line laser profilometer in the calibration plane coordinate system when the profilometer line disappears. This value is the minimum imaging height.

7. The calibration method for a line laser profilometer as described in claim 1, characterized in that, The calibration plane is provided with a calibration evaluation line; the Sc step, which obtains the coordinate transformation relationship between the line laser profilometer and the actuator end, also includes: Based on the coordinate transformation relationship between the line laser profilometer and the end effector obtained in step Sc5, calculate the pose H of the line laser profilometer when it projects the laser onto the mark evaluation line. L ; Based on H L Adjust the position of the actuator; Observe the overlap between the laser line projected onto the calibration plane by the line laser profilometer and the calibration evaluation line; if the overlap is greater than the threshold, repeat steps Sa to Sc; if the overlap is less than the threshold, the calibration is complete.

8. A method for quantitatively evaluating optical path deviation in a line laser profilometer, characterized in that, By applying the line laser profilometer calibration method as described in any one of claims 1 to 7, the coordinate transformation relationship between the line laser profilometer and the end effector of the actuator is obtained; By transforming the coordinates of the line laser profiler and the actuator end, the attitude of the line laser profiler relative to the calibration plane is adjusted so that the normal of the plane in which the laser of the line laser profiler is located is parallel to the calibration plane, and the direction of the laser angle bisector of the line laser profiler is parallel to the calibration plane. Adjust the distance between the line laser profilometer and the calibration plane so that the profile line appears in the acquisition software interface of the line laser profilometer; Calculate the angle between the contour line and the horizontal coordinate axis of the acquisition software interface to obtain the x-axis installation angle error of the imaging plane of the line laser profilometer; Obtain the coordinates of the midpoint of the contour line in the imaging coordinate system of the line laser profilometer. Combine this with the height value of the line laser profilometer relative to the calibration plane, and calculate the coordinate difference between the origin of the profilometer imaging coordinate system and the origin of the line laser profilometer calibration coordinate system in the corresponding axis direction.

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